Of Steel, Of Iron, Of Stone
by Seito
Summary: Dying Will Bullets weren't supposed to do /that/.


Thanks to **thepockythief** for helping with the plotting.

I FINALLY FINISHED THE CHRISTMAS PROMPTS I OWED PEOPLE -bricked- It only took a year.

But I do hope you guys enjoy it.

* * *

 _"Ciassou. I've been sent by Vongola to train you as their newest Decimo."_

 _"I have no idea what you're talking about, Reborn. But I cannot be Vongola's Decimo. I suggest you pick out another candidate."_

 _"You don't have a choice, Tsuna. Nono sent me to train you as Decimo."_

 _"That's still not happening. Look I have to get to school. We'll talk about this later."_

-.-.-.-.-.-.-.-.-.-.-.-

Reborn was made of steel, of iron, of stone. Unmovable, unrelenting, unforgiving. And yet, under the right circumstances, even steel, iron, stone yield and broke. This… this shook him.

Dying Will Bullets weren't supposed to do that.

Reborn was sure of many things, held confidence in the knowledge he had, never doubted his skills. He clawed his way to the top as the World's Greatest Hitman, fought for every second of it, bled and killed. There was no room for mistakes. Mistakes would cost him his life.

This was a mistake.

He had arrived in Namimori with low expectations and a relatively easy job in sight. It would be long, it would be frustrating, it would be annoying, but it shouldn't be difficult. Tsuna was similar to Dino. It shouldn't have been that hard. Everything went according to plan, until he fired the Dying Will Bullet.

Dying Will Bullets weren't supposed to do _that_.

He fired the bullet, expecting to be treated a hilarious outburst with Tsuna's clothes exploding off of him and him screaming about how he would confess to his crush. Instead, the bullet pierced Tsuna's forehead, knocking him back. Dying Will Flames exploded outward, coating the entire area in orange Sky Flames.

Only Tsuna didn't _get up_.

An uneasy feeling grew in the pit of Reborn's stomach when there was no yelling. The Dying Will Flames vanished, leaving Tsuna collapsed on the ground, unmoving. Reborn moved forward, a smidge of doubt beginning to grow.

"Tsuna?" Reborn asked, hoping for a response. He touched Tsuna's head, patting his cheek. There was no response.

The uneasy feeling doubled and Reborn could feel something was wrong. He made it a point to listen to his instincts and without any doubts he called for an ambulance.

The ride to hospital was a quiet one as Reborn sat watching the paramedics work on Tsuna. He watched as they took vitals and check for responsiveness. Tsuna remained unconscious the entire way. Only one thought remained in his head.

Dying Will Bullets _**weren't**_ supposed to _**do that**_.

-.-.-.-.-.-.-.-.-.-.-.-.-

"Tsu-kun?!"

He would never admit it, but Reborn felt a flinch of guilt strike his heart as a distraught Nana burst into Tsuna's hospital room. Tsuna had yet to awake, but multiple doctors and nurses had already reassured Reborn that it was only temporary.

"Sawada-san," the doctor stepped in the room.

"Sensei," Nana said. "I thought- it's too soon!"

"I'm sorry. It looks like your son's disease is beginning to get worse," the doctor said gently. "You might want to consider pulling him out of school."

"No, no," Nana said. "Tsu-kun wanted to go as long as he was able. It didn't matter how hard it was. He wasn't ready to give up."

"Sawada-san," the doctor said. "I know that. But you must be careful. The ten years for Juvenile Huntington's Disease is an average. It's possible it will hit Tsunayoshi much harder and much sooner."

Forgotten in the corner, Reborn froze. He ran that sentence over and over again in his head. Juvenile Huntington's Disease. No. Impossible. He slipped out of the room.

He found a quiet corner out in the hospital garden, hiding in the bushes and tried to wrap his mind around what he heard. Leon curled around his hand, trying to offer comfort. Reborn pulled out his smartphone, searching for information. He didn't know enough. His eyes soaked in the information, the pieces of the puzzles falling into place revealing a horrifying picture that Reborn hadn't even know.

How had he missed this? How had anyone missed this?

He stared at the short synopsis the internet had provided him, willing for the words to change.

 _Juvenile Onset Huntington's Disease (JHD)_

 _JHD is a form of Huntington's Disease that forms during childhood or adolescence. It is a hereditary neurodegenerative disorder that is characterized by progressively worsening motor, cognitive, behavioral, and psychiatric symptoms. Death occurs within ten years of the onset of JHD. There is no cure._

No cure. _No cure_. Suddenly everything about Tsuna's behavior and personality took on a new light. His clumsiness was a result of him starting to lose control over his motor functions. His bad grades were part of his struggles cognitively.

Reborn drew in a sharp breath of quiet horror. Dying Will Flames lived off one's lifeforce. But it took considerable energy and willpower to light them. Dying Will Bullet forcibly broke those bonds. Had firing the bullet cause Tsuna's new downward swing?

Ten years. Ten years within the onset. How long had Tsuna been diagnosed? How much longer did he have?

He felt sick to his stomach as he realized what Tsuna had been trying to tell him earlier this morning. Tsuna cannot be Decimo. He would be dead by then.

What had he _**done**_?

-.-.-.-.-.-.-.-.-.-.-.-.-

Reborn snuck back into Tsuna's room, passing Nana and the doctor who had moved down the hall to talk. He climbed onto Tsuna's bed and stared at his student. The pale pallor of Tsuna's face reminded Reborn too much of Luce who also wasted away by a disease that no one could cure. Reborn didn't think he would ever find himself in this situation again.

Reborn was made of steel, of iron, of stone. His heart was cold and frozen and he had little care for others. He was the World's Greatest Hitman. He didn't make mistakes.

Everything about this so far was a mistake. He didn't _know_. Ignorance was no excuse. He didn't know and now Tsuna paid the price for it.

"Reborn."

Reborn saw Tsuna stirred awake. A tired resignation flickered in his brown eyes. "I guess we'll have the conversation now," Tsuna said with a touch of a bitterness. "I cannot be Decimo, Reborn, but I'll be dead by the time I inherit it."

"I'm sorry," Reborn said with regret. This much he owed.

"You didn't know," Tsuna said.

But he should have. Information was vital for Reborn's job. Screw ups meant failure. There wasn't any mention of Tsuna being ill in any of the reports given to him. He should have double checked the information especially since he knew that Iemitsu hadn't been back home in years.

(Did Iemitsu even know? He doubted it.)

"You should find someone else," Tsuna said.

Right now the Vongola heir was the furthest thing from Reborn's mind. "Don't worry about that Tsuna," Reborn said.

The door slid open revealing the doctor and Nana. "Oh, you're awake Tsunayoshi. Let's take a look over," the doctor said.

Reborn slipped off the bed and out of the doctor's way.

-.-.-.-.-.-.-.-.-.-.-.-.-

Today had been a tiring and stressful day. It had been hours since Tsuna had been discharged from the hospital. Reborn teetered on the edge, unbalanced by all that he had learned. He felt like a rookie again, making mistakes that could have costed him his life.

He sat on Tsuna's desk, watching as Tsuna slept, unaware. The moonlight from the window showed the steady rise and fall of Tsuna's chest, a sure sign of life. For a split moment, Reborn saw his mother's sickly form overlap Tsuna's and his heart squeezed tight. It was like Reborn was ten again and unable to do anything.

Illness was something Reborn couldn't fight, couldn't kill, even with the devastating healing effects of his Sun Flames. He held everyone at arm's length, never allowing anyone close so that he would never have to feel that helpless. Luce slipped past the barriers first and Reborn was rewarded by watching her waste away as well. Now, Tsuna, far too young, had done the same.

No matter how strong he became, no matter how powerful, death marched on and the people Reborn allowed close always died in a way that Reborn could never prevent.

Heart heavy, Reborn left Tsuna's room and pulled out his phone. He punched in the numbers he had memorized and waiting for the other person to pick up.

"Reborn! I hope your trip was smooth. Have you met Tsunayoshi yet?"

"Nono," Reborn said, voice tight.

"Is everything all right?" Nono said, cheer dropping away.

"Tsuna cannot be Decimo," Reborn said.

"Now I know he's just a civilian, but -"

"He's dying, Nono," Reborn cut Nono off.

Nono went silence on the other line. "What? No," he sputtered.

Reborn rubbed his forehead. He could feel some sympathy for Nono. He had lost three sons, the fourth had rebelled against him. Now, Tsunayoshi whom Nono only knew from one visit and pictures was dying. All of Nono's hopes and dreams were pinned on Tsuna and that burned up, disappearing in a puff of smoke before it even came into fruition.

"Tsuna is dying," Reborn repeated. "It's incurable. He had a few years left and it's only going to progressively get worse. I suspect Dying Will Bullets will make it worse. There isn't any way to train him. There isn't any point."

Tsuna had filled him in on the details as they left the hospital with a grim voice. He stoically recited the information that the doctors had probably told him over and over. It was clinically delivered in a cold fashion as if his body wasn't beginning to betray him. Reborn took it all in, watching and observing. All the signs were now clear to him, the twitch and shake of Tsuna's hands that he received dismissed as restless nervous energy. The way Tsuna sometimes stumbled over his words becoming tongued tied, the subtle way he struggled to recall.

"They don't expect him to live past age seventeen," Reborn finished. If he made it to twenty it would be a miracle.

He felt so weary. Life was cruel. Reborn knew that better than anyone else. But it felt so wrong that it happened to people who were so bright and genuinely nice, like Tsuna, like Luce, like his mother.

A broken hitch of breath drew him out of his thoughts.

"I will be staying in Namimori," Reborn said. Regardless of the fact that Tsuna couldn't be Decimo, he was still Reborn's student and it was part of Reborn's fault for his sudden downward swing. He owed it to Tsuna to see this through until the end. Less than four years was too short. Far too short for someone as young as Tsuna.

He hung up, letting Nono to mourn in private.

-.-.-.-.-.-.-.-.-.-.-.-.-

Morning came too fast for Reborn's liking. He hadn't slept, turning Tsuna's situation over and over in his head. Reborn was a planner. He needed plans and backup plans on how to proceed.

"Good morning Reborn," Tsuna said, stretching. He rubbed his legs.

"Good morning Tsuna," Reborn greeted. He hopped onto Tsuna's bed. "You no longer have to worry about Vongola. I've informed Nono that you cannot be Decimo."

"Ah," Tsuna said. "When you be leaving?"

"If you let me, I would like to stay," Reborn said.

Tsuna's whipped his head to the side so fast that Reborn feared for whiplash. "What?" Tsuna whispered, stunned. "No. Reborn you don't have to."

"I want to," Reborn said firmly.

He did. He couldn't really explain the feeling. Guilt and regrets weren't things Reborn was used to dealing with. He was setting himself up for failure, but at the same time it was a pride thing. Reborn had accepted Tsuna as his student. Maybe Tsuna didn't really need a tutor, but at the same time Reborn couldn't find it in himself to just abandoned him either.

"I'm going to get so much worse Reborn," Tsuna said so softly. "You… you don't have to watch that happen."

There was no miracle cure waiting to happen. No amount of praying or hoping was going to make this better. This would be a wound that Reborn would deliberately inflict on his own heart. Honestly, he didn't really understand why he was doing this to himself.

"I know," Reborn said firmly. "Do you have a bucket list Tsuna?"

"A what?"

"A bucket list. It's a list of things you want to do before you die," Reborn said. "Like if you want to travel overseas or eat seafood from Hokkaido."

Tsuna blinked. "I… no?"

"We'll make a list then," Reborn said.

It was a silly and small thing. But Reborn was looking to put a positive spin on Tsuna's life. Reevaluating the information that Reborn knew and cross referencing, it was easy to see that Tsuna didn't have many positive and happy things in his life. Bullying and his nickname of Dame-Tsuna were just the tip of the iceberg.

"Well, I supposed there was one thing," Tsuna said thoughtfully. "I would like a friend."

Reborn blinked, mind instantly flashing to the violent and destructive relationship he had with the other Arcobaleno. "I'm not a very good friend."

Tsuna laughed. "It's not like I have a good frame of reference and we did start off on the wrong foot. Hello I'm Sawada Tsunayoshi. I like lions and hate cockroaches. Salisbury steak is my favorite food."

This boy was too forgiving. "Ciassou. I am Reborn. World's Greatest Hitman and the Sun Arcobaleno. This is my partner Leon. I like nami flavored miso soup, espresso and chaos."

Tsuna gave him a wide smile. "It's nice to meet you Reborn. Let's be friends."

"Very well," Reborn said.

He would protect that smile for as long as he could.

 _memento mori_

 _remember that you have to die_

* * *

 **For Inumaru12** who requested:

 _Basically, Tsuna finds out that he's very sick and more then likely not going to live to see his 16th bday and just continues through his life trying to enjoy it but at the same time not really seeing anything he does or himself as important. To make it worse, every time he uses his flames it makes his sickness worse. Then Reborn arrives to train Tsuna and basically finds out the kid is a ticking time bomb with one foot out the door and the kid just fucking smiles that painful smile and tells him that it's okay because he's dame-tsuna and it's not like anyone is gonna miss him anyway. It's just a great big mess of Tsuna trying to pretend it's okay and Reborn eventually helping him do everything he wants to do before he dies._

-.-.-

Man, finding a disease that would fit this requirement was probably the hardest part. While I do have more notes in this universe, I don't really have any intention of exploring it any further. (Mostly due to my lack of knowledge regarding JHD).

Please leave a review on your way out.


End file.
